Got stuck following a tutorial please help
They used the Loop Subdivide tool. It creates loop cut(s) around the area selected by the user.

hotkey: ctrl + r
a yellow line shows what section will be cut - click to confirm cutting this section

Once confirming the section to cut:
 scroll wheel increases/decreases cuts
move mouse to slide where the cut will happen
click again to finally cut

Here's the Blender documentation for further reading: Blender Loop Subdivide
Good luck with the tutorial, hope this helps!